For years, dentists have practiced the art of replacing missing teeth of their patients with various materials, including metal restorations. Typically, the metal restorations comprise precious metals such as gold and silver. In many cases, the natural coloring of these metal restorations were not pleasing to the patient if they were used to replace anterior or front teeth.
In order to achieve benefits such as maximizing the aesthetic appeal and/or improving the life of the restoration, porcelain-to-metal technology was developed and introduced to the dental profession.
In order to maximize the aesthetic appeal to dental patients, one technique coats the metal with opaque tooth color shaded porcelain that closely matched the patient's natural dentition. In this technique, a mixture of powdered opaque porcelain and distilled water is mixed and the opaque porcelain was applied by brush to mask out the color of the alloy. Then a translucent porcelain is applied and shaped to a tooth form and a transparent glaze is applied with a brush or instrument. However, this is both tedious and time consuming.
More specifically, a typical prior art technique utilized to apply opaque or porcelain to a metal restoration is by brush or instrument. In this process, an opaque (or opaque porcelain) is chosen as closely as possible matching the color and shade of the patient's teeth. The opaque is then mixed with water or an opaque liquid to a creamy consistency. The opaque liquid allows complete wetting of the surface of the restoration so that the opaque will properly attach and coat.
The restoration is carefully cleaned and all dirt and oil is removed. The restoration is then dampened with distilled water or opaque liquid to aid in wetting. Next, the brush is dipped into the opaque mixture and a thin coating of opaque is applied to the restoration by gently tapping the brush and restoration. Once completely covered, the restoration is fired to dry and set the opaque. An opaque mixture of thicker consistency is then made and the application and firing procedure repeated to add a second, thicker coating.
Additionally, a formula of a compatible ceramic stains or colors may be brushed on the restoration and allowed to fire. The glaze is then brushed onto the surface of the restoration and fired so that it appears to be wet and with characterization of stains to match the natural dentition. If desired, an additional application may be applied and fired again to achieve the desired results. The restoration is then finished by polishing any exposed metal alloy and readied for cementation or bonding onto the patients tooth.
While it is possible to apply a somewhat even or smooth coating of opaque or glaze with brush techniques, they require a great deal of familiarity or skill. For example, if glaze or opaque is mixed too thinly it may be hard to control, possibly resulting in a patchy glazed surface on the restoration, and therefore requiring another application of glaze. Furthermore, the patchy or inconsistent surface may exhibit poor bonding characteristics.
Also, a mixture too thick could result in opaque being too thick, resulting in a porcelain restoration with no vitality or translucency. Thick glaze fills up the occlusal anatomy or surface details thereby affecting the life-like appearance of the restoration. In applying a thick opaque and glaze it tends to puddle at the margin areas resulting in thick margins that contributes to periodontal disease. Thick glaze fills in details like cervical grooves of anterior teeth and detailed anatomical grooves of posterior teeth of the restoration causing a light discoloration of the restoration. This results in reduction or grinding away of the glaze to avoid a shade or color mismatch. It may also impinge the patients gum tissue, which could result in periodontal gum disease. A thick coating could also result in a poor bond of glaze to porcelain, undesirable white spots discussed above may also present themselves prominently as well. Additionally, a coating that is too thick may lead to bubbling during firing and poor bonding from incomplete wetting of the alloy surface.
In summary, the brush method is very technique sensitive, requiring a skilled ceramist with knowledge of dental anatomy and tissue sensitivities of patients. Additionally, the time that technician must devote to each restoration is costly.
Another method is an airbrush technique, which involved modifying a standard airbrush apparatus. However, this procedure included the tedious steps using multiple airbrush paint jars, test spraying to check spray consistency, and time consuming cleaning steps. Therefore, the airbrush technique is usually practical in a custom laboratory situation, not in a typical production laboratory.
Accordingly, one of ordinary skill in the dental restoration art or ceramic art recognizes the need for a new, easier technique. The present invention addresses this need. The present invention provides an easier method to apply opaque porcelain, stain and/or glaze multiple units in a fraction of the time it would take a skilled technician to do just one unit. The delivery systems of embodiments of the present invention both simplify the opaque and glaze application in a reliable and smooth coating, while also standardizing the process and reducing the cost of producing finished restorations.